Impact of FKBP52 on cell proliferation and hormone-dependent cancers.

FKBP52 (FK506 binding protein 52) (gene name FKBP4) is a 52-kDa protein that belongs to the FKBP family; it binds to the immunosuppressant FK506 and has proline isomerase activity. In addition to its FK domain-containing peptidylprolyl isomerase (PPIase) activity, FKBP52 also acts as a co-chaperone through the tetratricopeptide repeat (TPR) domain that mediates binding to heat shock protein 90 (HSP90). Previous studies have reported that FKBP52 is associated with hormone-dependent, stress-related, and neurodegenerative diseases, revealing its diverse functions. In particular, the effects of FKBP52 on cancer have attracted considerable attention. FKBP52 promotes the growth of hormone-dependent cancers by activating steroid hormone receptors (SHRs). Recent studies have shown that the expression of FKBP52 is increased not only in steroid hormone-dependent cancer cells but also in colorectal, lung, and liver cancers, revealing its diverse functions that contribute to cancer growth. This review summarizes reports related to hormone-dependent cancer and cell proliferation in terms of the structure of FKBP52 and its function on interacting molecules.